Problem: Solve for $q$ : $15 = -7 + q$
Answer: Add $7$ to both sides: $ \begin{eqnarray} \\ \hphantom{15 {+ 7}} &\hphantom{=}& \hphantom{q} \\ 15 &=& -7 + q \\ \\ {+7} && {+7} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 15 {+ 7} &=& q \\ \end{eqnarray} $ Simplify. $ q = 22$